3of132.Marconi was in his patrol car writing a traffic citation after pulling over a driver around 11:45 a.m. near police headquarters downtown.

Photo: Edward A. Ornelas, Staff / San Antonio Express-News

4of133.During the traffic stop, a black Mitsubishi Galant pulled up behind Marconi’s patrol car. The suspect in the Galant approached the cruiser and proceeded to shoot Marconi twice, striking him in the head, before fleeing the scene, police said.

5of134. Four hours earlier, McKane entered police headquarters to ask about custody of a child before leaving in a Mitsubishi Galant, according to an affidavit.Photo: Courtesy photo

7of136. McKane told reporters he “lashed out at somebody who didn’t deserve it” due to an ongoing custody battle for his son.Photo: Matthew Busch, For The San Antonio Express-News

8of137.An employee for a tire shop off Bandera Road told police on Nov. 21, 2016 told police he sold McKane the rims and tires on the Mitsubishi several weeks before the shooting, according to an affidavit. The affidavit states that the employee said McKane was still paying for the rims on a payment plan.

9of138. mySA.com found McKane was married hours after he allegedly shot Marconi. He was married to Christian Chanel Fields, 27, who owns the white Buick McKane was found in Nov. 21, 2016.Photo: Bexar County

10of139. Fields, 27, has been arrested on at least two theft charges in Harris County, records show. She was sentenced to deferred adjudication in lieu of a conviction for a 2010 state jail felony charge, records show. Fields was sentenced in a misdemeanor theft case in May 2011, according to court records.Photo: Facebook.com

SAPD Chief William McManus said the suspect, now the target of a massive manhunt, entered the downtown headquarters at 315 S. Santa Rosa around 7:45 a.m.

About four hours later, police say, the suspect approached the 20-year SAPD veteran's car on the south side of the building as he carried out a traffic stop on another driver and shot him twice through the passenger window of Marconi's patrol cruiser.

"I think the uniform was the target," McManus said. “...We consider this suspect to be extremely dangerous to the police and the public."

Surveillance footage released by police Monday morning shows a dark-skinned man, who police have described as approximately 5 feet 7 inches to 6 feet tall, pacing out front of police headquarters before entering the building.

McManus said the suspect spoke to a clerk for around 20 seconds before leaving. McManus said no officers were in the building at the time, but refused to elaborate on the interaction, citing an ongoing investigation.

Officials released few other details on the suspect, saying they're not sure whether he is from the area and warning people to report any sightings to police.

The suspect was driving a black Mitsubishi Galant with chrome wheels when he pulled up behind Marconi before opening fire, police said.

Local police, in coordination with federal agencies, have questioned a number of individuals, including the driver who was being pulled over by Marconi, since the incident, but all of have been released, McManus said.

McManus said the department is encouraging officers to pair up when they patrol neighborhoods and respond to 911 calls, although it’s not required.

The San Antonio Police Department headquarters is a multi-story building located on the corner of Santa Rosa Avenue and Nueva Street. The building has two sets of glass doors that lead to a spacious lobby with couches, an information center and a security check, which leads to the rest of the building. The information center, where the suspect is seen in video surveillance talking to a clerk, is enclosed in glass.

Crime Stoppers is offering up to $10,000 for information leading to the arrest of a suspect in the capital murder, while Texas Gov. Greg Abbott announced Monday morning his office is offering an additional $15,000 for that information.

McManus described the situation as everyone’s "worst nightmare."

"It's always difficult, especially in this day and age, where police are being targeted across the country," McManus said.

Marconi on Sunday was transported to San Antonio Military Medical Center, where he was later pronounced dead.

Marconi's family released a statement Monday asking for privacy.

"At this time, the Marconi family would like to give thanks from the bottom of our hearts for the outpouring of support, prayers and love we have received. At this time, we would appreciate privacy to mourn the loss of a wonderful father, brother, grandfather, friend and last, but not least, a peace officer," the family said, thanking the San Antonio community and the support they received from the country.

The last San Antonio police officer killed was Robert Deckard Jr., who died in December 2013.

Deckard, 32, was a seven-year veteran at SAPD who was shot Dec. 8, 2013 as he pursued two robbery suspects. The chase reached speeds of 115 mph, police said. Deckard died after 13 days in intensive care.